It is also characterized by the presence of backfills (40 % porosity) and filled shafts on different levels of the ore deposit.
when ore was mined from Carboniferous shale, the additional stresses in the rocks on the first level were so intense that mining from bottom to top was practically impossible, because the time-dependent phenomena were so intensive that backfills have still not stabilized.
Since there is always a the and/or other apparatus on the end of the barrel in a production situation, the screw necessarily backfills for a certain distance to develop the pressure necessary to overcome the resistance caused by these elements.
If the backfill is not adequate, the screw output will be unstable and even the smallest variation in output entering the discharge section will cause the screw to vary in its fill length.
But in written requests to city officials, LAPD brass asked for nearly $600,000 to make promotions and backfills for the new station.
When a new police station opens in Mission Hills next January, it will further strain the LAPD's limited officer ranks and cost about $364,000 to promote officers and backfill positions, officials said Monday.
However, there are also problems, such as more difficult rheology as the paste has higher pressure losses per unit length of pipe as compared to hydraulic (low density) backfills.
Foam reduces and in most cases eliminates segregation of the solids/water in high density backfills during transport
In a continuous single-pass operation, Dynapad processes and backfills rocky spoil in a four-layered system while installing geotextile fabric on top of the padding layer.
FELCO's backfill conveyor places material in a hopper that travels the length of the conveyor and is returned to the trench on a cross conveyor.
PCCE's work has shown that "despite the large differences in constituent materials and flow behaviour, a common approach can be applied to analysing the flow of all hydraulic backfills